托管 bean class java.time.ZonedDateTime 用于托管 bean managedBean 没有声明 public 无参数构造函数
Managed bean class java.time.ZonedDateTime for managed bean managedBean doesn't declare a public no-argument constructor
为了获取当前日期，我在faces-config.xml中声明了一个托管bean，如下所示。
<managed-bean>
<managed-bean-name>currentDate</managed-bean-name>
<managed-bean-class>java.time.ZonedDateTime</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
早些时候，我一直在使用 org.joda.time.DateTime 并且工作正常。这个 bean 可以在 EL 中访问，如下所示。
<h:outputText value="#{currentDate}" converter="#{converter}"/>
然而，这会导致抛出以下异常。
16:15:29,984 SEVERE [javax.enterprise.resource.webcontainer.jsf.application] (default task-16) Error Rendering View[/admin_side/Home.xhtml]: com.sun.faces.mgbean.ManagedBeanCreationException: Unable to create managed bean currentDate. The following problems were found:
- Managed bean class java.time.ZonedDateTime for managed bean currentDate doesnt declare a public no-argument constructor.
at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:265)
at com.sun.faces.el.ManagedBeanELResolver.resolveBean(ManagedBeanELResolver.java:257)
at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:117)
at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
at com.sun.el.parser.AstIdentifier.getValue(AstIdentifier.java:116)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:226)
at org.jboss.weld.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
at org.jboss.weld.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
at javax.faces.component.UIOutput.getValue(UIOutput.java:174)
at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getValue(HtmlBasicInputRenderer.java:205)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getCurrentValue(HtmlBasicRenderer.java:355)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeEnd(HtmlBasicRenderer.java:164)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:920)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1863)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:890)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:304)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:309)
at com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:114)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:890)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:458)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:134)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:659)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:86)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:130)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:78)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at io.undertow.websockets.jsr.JsrWebSocketFilter.doFilter(JsrWebSocketFilter.java:151)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at org.omnifaces.facesviews.FacesViewsForwardingFilter.filterExtensionLess(FacesViewsForwardingFilter.java:128)
at org.omnifaces.facesviews.FacesViewsForwardingFilter.doFilter(FacesViewsForwardingFilter.java:89)
at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:108)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at filter.NoCacheFilter.doFilter(NoCacheFilter.java:33)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at org.omnifaces.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:122)
at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:108)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:85)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
at io.undertow.server.handlers.DisableCacheHandler.handleRequest(DisableCacheHandler.java:33)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.security.handlers.AuthenticationConstraintHandler.handleRequest(AuthenticationConstraintHandler.java:51)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
at io.undertow.servlet.handlers.security.ServletSecurityConstraintHandler.handleRequest(ServletSecurityConstraintHandler.java:56)
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:72)
at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:282)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:261)
at io.undertow.servlet.handlers.ServletInitialHandler.access[=15=]0(ServletInitialHandler.java:80)
at io.undertow.servlet.handlers.ServletInitialHandler.handleRequest(ServletInitialHandler.java:172)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:199)
at io.undertow.server.HttpServerExchange.run(HttpServerExchange.java:774)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
他们称他们为Value-based Classes。因此，这样的 类 是不可变的，并且没有 public 无参数构造函数，因此是例外。
具体问题不需要全部参考。
Some classes, such as java.util.Optional and
java.time.LocalDateTime, are value-based. Instances of a value-based
class:
- are final and immutable (though may contain references to mutable objects); have implementations of
equals(), hashCode(),
and toString() which are computed solely from the instance's state
and not from its identity or the state of any other object or
variable;
- make no use of identity-sensitive operations such as reference equality (
==) between instances, identity hash code of instances, or
synchronization on an instances's intrinsic lock;
- are considered equal solely based on
equals(), not based on reference equality (==);
- do not have accessible constructors, but are instead instantiated through factory methods which make no commitment as to
the identity of returned instances;
- are freely substitutable when equal, meaning that interchanging any two instances
x and y that are equal according to equals() in
any computation or method invocation should produce no visible
change in behavior.
A program may produce unpredictable results if it attempts to
distinguish two references to equal values of a value-based class,
whether directly via reference equality or indirectly via an appeal to
synchronization, identity hashing, serialization, or any other
identity-sensitive mechanism. Use of such identity-sensitive
operations on instances of value-based classes may have unpredictable
effects and should be avoided.
拯救什么，转向java.util.Date / java.util.Calendar?
在 WildFly 9.0.2 final 中使用 Mojarra 2.2.12。
不幸的是，这确实是一个技术限制，无法通过 "old fashioned" <managed-bean> 方法解决。
鉴于未来可能会弃用 JSF bean 管理 Java EE 版本以支持 CDI，并且您使用 WildFly 实际上 运行 一个支持 CDI 的容器，您最好转向 CDI 方法。在 CDI 中，这可以通过 so-called producer 来实现。
@RequestScoped
public class CurrentDateProducer {
@Produces
@Named
public ZonedDateTime getCurrentDate() {
return ZonedDateTime.now();
}
}
它将以 #{currentDate} 预期的方式提供。
为了获取当前日期，我在faces-config.xml中声明了一个托管bean，如下所示。
<managed-bean>
<managed-bean-name>currentDate</managed-bean-name>
<managed-bean-class>java.time.ZonedDateTime</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
早些时候，我一直在使用 org.joda.time.DateTime 并且工作正常。这个 bean 可以在 EL 中访问，如下所示。
<h:outputText value="#{currentDate}" converter="#{converter}"/>
然而，这会导致抛出以下异常。
16:15:29,984 SEVERE [javax.enterprise.resource.webcontainer.jsf.application] (default task-16) Error Rendering View[/admin_side/Home.xhtml]: com.sun.faces.mgbean.ManagedBeanCreationException: Unable to create managed bean currentDate. The following problems were found:
- Managed bean class java.time.ZonedDateTime for managed bean currentDate doesnt declare a public no-argument constructor.
at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:265)
at com.sun.faces.el.ManagedBeanELResolver.resolveBean(ManagedBeanELResolver.java:257)
at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:117)
at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
at com.sun.el.parser.AstIdentifier.getValue(AstIdentifier.java:116)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:226)
at org.jboss.weld.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
at org.jboss.weld.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
at javax.faces.component.UIOutput.getValue(UIOutput.java:174)
at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getValue(HtmlBasicInputRenderer.java:205)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getCurrentValue(HtmlBasicRenderer.java:355)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeEnd(HtmlBasicRenderer.java:164)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:920)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1863)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:890)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:304)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:309)
at com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:114)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:890)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:458)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:134)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:659)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:86)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:130)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:78)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at io.undertow.websockets.jsr.JsrWebSocketFilter.doFilter(JsrWebSocketFilter.java:151)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at org.omnifaces.facesviews.FacesViewsForwardingFilter.filterExtensionLess(FacesViewsForwardingFilter.java:128)
at org.omnifaces.facesviews.FacesViewsForwardingFilter.doFilter(FacesViewsForwardingFilter.java:89)
at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:108)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at filter.NoCacheFilter.doFilter(NoCacheFilter.java:33)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at org.omnifaces.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:122)
at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:108)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:85)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
at io.undertow.server.handlers.DisableCacheHandler.handleRequest(DisableCacheHandler.java:33)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.security.handlers.AuthenticationConstraintHandler.handleRequest(AuthenticationConstraintHandler.java:51)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
at io.undertow.servlet.handlers.security.ServletSecurityConstraintHandler.handleRequest(ServletSecurityConstraintHandler.java:56)
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:72)
at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:282)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:261)
at io.undertow.servlet.handlers.ServletInitialHandler.access[=15=]0(ServletInitialHandler.java:80)
at io.undertow.servlet.handlers.ServletInitialHandler.handleRequest(ServletInitialHandler.java:172)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:199)
at io.undertow.server.HttpServerExchange.run(HttpServerExchange.java:774)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
他们称他们为Value-based Classes。因此，这样的 类 是不可变的，并且没有 public 无参数构造函数，因此是例外。
具体问题不需要全部参考。
Some classes, such as
java.util.Optionalandjava.time.LocalDateTime, are value-based. Instances of a value-based class:
- are final and immutable (though may contain references to mutable objects); have implementations of
equals(),hashCode(), andtoString()which are computed solely from the instance's state and not from its identity or the state of any other object or variable;- make no use of identity-sensitive operations such as reference equality (
==) between instances, identity hash code of instances, or synchronization on an instances's intrinsic lock;- are considered equal solely based on
equals(), not based on reference equality (==);- do not have accessible constructors, but are instead instantiated through factory methods which make no commitment as to the identity of returned instances;
- are freely substitutable when equal, meaning that interchanging any two instances
xandythat are equal according toequals()in any computation or method invocation should produce no visible change in behavior.A program may produce unpredictable results if it attempts to distinguish two references to equal values of a value-based class, whether directly via reference equality or indirectly via an appeal to synchronization, identity hashing, serialization, or any other identity-sensitive mechanism. Use of such identity-sensitive operations on instances of value-based classes may have unpredictable effects and should be avoided.
拯救什么，转向java.util.Date / java.util.Calendar?
在 WildFly 9.0.2 final 中使用 Mojarra 2.2.12。
不幸的是，这确实是一个技术限制，无法通过 "old fashioned" <managed-bean> 方法解决。
鉴于未来可能会弃用 JSF bean 管理 Java EE 版本以支持 CDI，并且您使用 WildFly 实际上 运行 一个支持 CDI 的容器，您最好转向 CDI 方法。在 CDI 中，这可以通过 so-called producer 来实现。
@RequestScoped
public class CurrentDateProducer {
@Produces
@Named
public ZonedDateTime getCurrentDate() {
return ZonedDateTime.now();
}
}
它将以 #{currentDate} 预期的方式提供。